The present invention relates to internal combustion engines; more particularly, to devices for controlling systems in an internal combustion engine; and most particularly, to an assembly for retaining the solenoid deactivation control valves and for providing positive crankcase ventilation (PCV).
In conventional prior art four-stroke internal combustion engines, the mutual angular relationships of the crankshaft, camshaft, and valves are mechanically fixed; that is, the valves are opened and closed fully and identically with every two revolutions of the crankshaft, fuel/air mixture is drawn into each cylinder in a predetermined sequence, ignited by the sparking plug, and the burned residue discharged. This sequence occurs irrespective of the rotational speed of the engine or the load being placed on the engine at any given time.
It is known that for much of the operating life of a multiple-cylinder engine, the load might be met by a functionally smaller engine having fewer firing cylinders, and that at low-demand times fuel efficiency could be improved if one or more cylinders of a larger engine could be withdrawn from firing service. It is known in the art to accomplish this by de-activating the valve train leading to pre-selected cylinders in any of various ways, such as by providing special valve lifters having internal locks which may be switched on and off either electrically or hydraulically. Such switching is conveniently performed via a hydraulic manifold assembly that utilizes electric solenoid valves to selectively pass engine oil to the lifters upon command from an engine control module (ECM). Such a manifold assembly is often referred to in the art as a Lifter Oil Manifold Assembly (LOMA).
It is a principal object of the present invention to provide an assembly for retaining the solenoid valves and for positive crankcase ventilation comprising a minimum number of components which then may be easily fabricated, and preferably which are formed of a suitable thermoplastic polymer such that the components may be fusibly joined without threaded fasteners as by vibration welding.
Briefly described, a hydraulic manifold assembly for variable actuation of engine valves includes first (top) and second (bottom) plates having portions of oil flow passages, or galleries, integrally molded therein. The plates are formed preferably by injection molding of a suitable high temperature thermoplastic polymer. The plates are joined together as by cementing or preferably by fusion welding (vibration welding) along mating surfaces, obviating the need for separate fasteners and for internal seals on the flow passages. The hydraulic manifold assembly further comprises a retainer for retaining a plurality of individual solenoid-actuated valves in operational disposition in sockets formed in the plates.
In accordance with this invention, the retainer is also formed of a moldable polymer and with air passageways so as to function simultaneously as a PCV baffle that attaches to the hydraulic manifold assembly via integrally molded releasable snap clips. Alternatively, the retainer can be attached to a polymer hydraulic manifold assembly or to a conventional metal hydraulic manifold assembly via bolts or similar attachment means. The present invention results in a weight savings and a substantial savings in be manufacturing cost over prior art assemblies formed of cast aluminum.